Hello all! I learnt a few idioms and tried to use it but don't know whether I did it correct. Would you mind checking them?
1-)A: What do you think about
C?B: I don't like him, he's a bit selfish.
And then C comes
A: Oh!
Speak of the devil!2-) A: Bla bla bla...
B: Can you
put a sock in it. ( Is this idiom informal? Does it look so rude?
3-) A: You really don't want to hang out with those kind of girls. They are a dime a dozen.
4-) A-) What do you think about Messi?
B-) I think he's good compared to Ronaldo but...
C-) Who is 'he'? It's all Greek to me. Can you explain the situation?
5-) Barcelona wins over Real Madrid last 5 matches.
Barcelona fan: Stop beating a dead horse. You will never win.
Or
A guy is banned from EnglishForward and is trying to talk with an admin;
A: Can you please unban me? I'll never do it again.
Admin: Stop beating a dead horse please, there is no point of insisting. It won't happen.
6-) A: Hey. I won the lottery!!!!
B: Really? How much money have you won?
A: Uhm, approximately $500.000
C: Stop pulling B's leg. You did not win anything.
7-) An employee becomes late for work thrice in a row.
Boss: It's the last straw. I'm sorry but we will not work with you anymore.

Child: I want to watch this match so much, mom!
Mom: Why do you want it so much?
Child: This type of matches happens once in a blue moon, I don't want to miss it.
9-) A-) I think we should hire Mr. Black. Would you mind if I
hire/
hired him?
B-) No, I would not mind! I'm glad we see eye to eye.
10-) Child: Dad, Can we buy this toy please?
Dad: I'm sorry we can't. It cost an arm and a leg.
11-) A: We must fire one, which one would you prefer? C or D?
B: I really don't know. I like both of them. I'd like to sit on the fence and let you do the alone.
12-) And the last idiom is fall between two stools. But I can't think of any examples well. Would you mind giving an example?
Sorry for the mistakes I made. Could you also correct them please if there is any? Thanks.